Add the OpenReadOnly() OS method to fix a bug in the pager. (CVS 257)

FossilOrigin-Name: 82db5456c9817283d725daf4e1081d32a71466ad

manifest

@@ -1,5 +1,5 @@
-C Trying\sto\sget\sthe\sOS\sabstraction\slayer\sto\swork.\s(CVS\s256)
-D 2001-09-19T13:22:39
+C Add\sthe\sOpenReadOnly()\sOS\smethod\sto\sfix\sa\sbug\sin\sthe\spager.\s(CVS\s257)
+D 2001-09-19T13:58:44
 F Makefile.in 1d9592c4aeedd3643b2e1dfa037ce5faf54805a3
 F README 51f6a4e7408b34afa5bc1c0485f61b6a4efb6958
 F VERSION 3861a21803fcd9eb92a403027b0da2bb7add4de1
@@ -16,9 +16,9 @@ F src/expr.c 343a515a4abaf60e9e26c7412aa8c43fd3eae97d
 F src/insert.c b34860ea58525754f18bde652f74161295ca2455
 F src/main.c 5e5794eea3316dd3a63c112ccdcc997b9118f345
 F src/md5.c 52f677bfc590e09f71d07d7e327bd59da738d07c
-F src/os.c 6ed6f61915807b1b4578398b4e797e55b12db4ab
-F src/os.h 2528414d4d441e86cf458b7520ed7f629d446d70
-F src/pager.c 28c8a641601b81a11454de3015d3d796e31ea182
+F src/os.c 43735db052288f8bfee56e09dfa293c202ff93a3
+F src/os.h 6d627d8629a204c474cf13aa098654658378a81f
+F src/pager.c a77c7fd3f33c0c6834a042b9b0d4a8128553532e
 F src/pager.h a0d4c5ae271914aa07b62aee0707997d6932b6ca
 F src/parse.y 2bcf47bb8e6afd8bc10aebd555fa07b73905bee4
 F src/printf.c b1e22a47be8cdf707815647239991e08e8cb69f9
@@ -96,7 +96,7 @@ F www/opcode.tcl cb3a1abf8b7b9be9f3a228d097d6bf8b742c2b6f
 F www/sqlite.tcl cb0d23d8f061a80543928755ec7775da6e4f362f
 F www/tclsqlite.tcl 06f81c401f79a04f2c5ebfb97e7c176225c0aef2
 F www/vdbe.tcl 0c8aaa529dd216ccbf7daaabd80985e413d5f9ad
-P 22132ce18cad31482cdb9b380cedc3f53bc532b8
-R f2b9b288263979b8bf39b2aa8c086069
+P abff526d005b3b46904de091753cc79548739ad8
+R 4864863de07f710a3f6b561c261f5e5d
 U drh
-Z a1f7206e19ddb2d1a7062a107b29fcdc
+Z e4c492c8b9528b70a7181a2203d31493

manifest.uuid

@@ -1 +1 @@
-abff526d005b3b46904de091753cc79548739ad8
+82db5456c9817283d725daf4e1081d32a71466ad

src/os.c

@@ -28,9 +28,9 @@
 # define OS_WIN 0
 #endif
 #if OS_UNIX
+# include <unistd.h>
 # include <fcntl.h>
 # include <sys/stat.h>
-# include <unistd.h>
 # include <time.h>
 #endif
 #if OS_WIN
@@ -183,6 +183,39 @@ int sqliteOsOpenExclusive(const char *zFilename, OsFile *pResult){
 #endif
 }
 
+/*
+** Attempt to open a new file for read-only access.
+**
+** On success, write the file handle into *pResult and return SQLITE_OK.
+**
+** On failure, return SQLITE_CANTOPEN.
+*/
+int sqliteOsOpenReadOnly(const char *zFilename, OsFile *pResult){
+#if OS_UNIX
+  int fd = open(zFilename, O_RDONLY);
+  if( fd<0 ){
+    return SQLITE_CANTOPEN;
+  }
+  *pResult = fd;
+  return SQLITE_OK;
+#endif
+#if OS_WIN
+  HANDLE h = CreateFile(zFilename,
+     GENERIC_READ,
+     0,
+     NULL,
+     OPEN_EXISTING,
+     FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
+     NULL
+  );
+  if( h==INVALID_HANDLE_VALUE ){
+    return SQLITE_CANTOPEN;
+  }
+  *pResult = h;
+  return SQLITE_OK;
+#endif
+}
+
 /*
 ** Create a temporary file name in zBuf.  zBuf must be big enough to
 ** hold at least SQLITE_TEMPNAME_SIZE characters.
@@ -357,15 +390,10 @@ int sqliteOsLock(OsFile id, int wrlock){
 #if OS_UNIX
   int rc;
   struct flock lock;
-memset(&lock, 0, sizeof(lock));
   lock.l_type = wrlock ? F_WRLCK : F_RDLCK;
   lock.l_whence = SEEK_SET;
-  lock.l_start = 0L;
-  lock.l_len = 1024L;
-printf("LOCK %s %d\n",wrlock?"WRITE":"READ",id);
+  lock.l_start = lock.l_len = 0L;
   rc = fcntl(id, F_SETLK, &lock);
-fcntl(id, F_GETLK, &lock);
-printf("rc=%d why=%d\n",rc,lock.l_type);
   return rc==0 ? SQLITE_OK : SQLITE_BUSY;
 #endif
 #if OS_WIN
@@ -385,9 +413,7 @@ int sqliteOsUnlock(OsFile id){
   struct flock lock;
   lock.l_type = F_UNLCK;
   lock.l_whence = SEEK_SET;
-  lock.l_start = 0L;
-  lock.l_len = 1L;
-printf("UNLOCK %d\n",id);
+  lock.l_start = lock.l_len = 0L;
   rc = fcntl(id, F_SETLK, &lock);
   return rc==0 ? SQLITE_OK : SQLITE_IOERR;
 #endif

src/os.h

@@ -40,6 +40,7 @@ int sqliteOsDelete(const char*);
 int sqliteOsFileExists(const char*);
 int sqliteOsOpenReadWrite(const char*, OsFile*, int*);
 int sqliteOsOpenExclusive(const char*, OsFile*);
+int sqliteOsOpenReadOnly(const char*, OsFile*);
 int sqliteOsTempFileName(char*);
 int sqliteOsClose(OsFile);
 int sqliteOsRead(OsFile, void*, int amt);

src/pager.c

@@ -18,7 +18,7 @@
 ** file simultaneously, or one process from reading the database while
 ** another is writing.
 **
-** @(#) $Id: pager.c,v 1.22 2001/09/19 13:22:40 drh Exp $
+** @(#) $Id: pager.c,v 1.23 2001/09/19 13:58:44 drh Exp $
 */
 #include "sqliteInt.h"
 #include "pager.h"
@@ -636,12 +636,12 @@ int sqlitepager_get(Pager *pPager, Pgno pgno, void **ppPage){
     /* If a journal file exists, try to play it back.
     */
     if( sqliteOsFileExists(pPager->zJournal) ){
-       int rc, readOnly;
+       int rc;
 
        /* Open the journal for exclusive access.  Return SQLITE_BUSY if
        ** we cannot get exclusive access to the journal file
        */
-       rc = sqliteOsOpenReadWrite(pPager->zJournal, &pPager->jfd, &readOnly);
+       rc = sqliteOsOpenReadOnly(pPager->zJournal, &pPager->jfd);
        if( rc==SQLITE_OK ){
          pPager->journalOpen = 1;
        }